1. Technical Field
This invention relates to a clamping apparatus of the type which linearly moves a clamp rod to a clamping position after having rotated it from a retreated position to an unclamping position.
Explanation of Earlier Technology
Conventionally, there has been existing a clamping apparatus disclosed in Japanese Utility Model Publication No. 60-18267 as an example of the rotary clamping apparatus of this type.
More specifically, it is a clamping apparatus which comprises a housing provided with an upper end wall slidably supporting a clamp rod, a rotation actuating shaft being inserted into a lower portion of the clamp rod, an engaging pin fixed onto the clamp rod being engaged with a guide groove of the shaft. The clamp rod is rotated along an inclined cam portion of the guide groove and thereafter moved to a clamping position along a linear portion of the guide groove.
The above-mentioned conventional technique requires a predetermined engaging gap between the engaging pin and the guide groove and therefore cannot guide the clamp rod straightly. Accordingly, it encounters a difficulty in linearly driving the clamp rod with accuracy at the time of clamping.